Method of mounting a sensor arrangement in a tubular member, and use of the method

ABSTRACT

For use in the monitoring of a tubular member ( 1 ) having at least a helically wound reinforcement layer ( 10 ), the invention provides a method of mounting a sensor arrangement ( 17, 18 ), wherein the reinforcement layer is formed with a groove ( 16 ) which is filled with a liquid material ( 19 ), such as an epoxy type, and wherein the sensor arrangement is passed into the liquid material by means of a pressure applied by a roller prior to the solidification of the liquid material. In a preferred embodiment, the groove is formed in the reinforcement layer before this is helically wound on the tubular member. Hereby, the sensor arrangement is arranged well-protected without any risk of damage, which may e.g. occur if the tubular member is of the unbonded type, where the reinforcement layer may consist of two layers that may move relative to each other. Furthermore, the sensor arrangement is protected against the external mechanical impacts that may occur if the groove is provided in a reinforcement layer which is freely exposed to the surroundings. The invention is particular suitable for tubular members, including umbilicals that are used for the recovery, refining and transport of oil and gasses.

The invention relates to a method of mounting a sensor arrangement in atubular member, wherein at least a reinforcement layer is provided onthe tubular member by helical winding. Moreover, the invention relatesto a tubular member comprising a sensor arrangement.

The invention moreover relates to a use of the method and a tubularmember comprising a sensor arrangement.

Tubular members of the said type, which are used inter alia for thetransport of oil and gas, are well-described in the patent literature,and by way of example reference is made to JP 3265781, FR 2764669 and WO00/36324.

The pipes are widely used for many different purposes in the offshoreindustry.

An ordinary use is for the transport of water, gas and crude oil betweeninstallations at an oil field, or in connection with theloading/unloading and transport of oil products. Such pipes are alsocalled flow-lines, risers or jumpers.

Another use is for the transport of process liquids and hydraulic oiland for the carrying of light and power from an installation positionedat the surface of the sea and down to the oil wells on the seabed.

This type of pipes is not directly involved in the transport of oil andgas, but is necessary for the supply of the process liquids which, asmentioned, are to be used for the recovery of oil, as well as for therunning of hydraulic pipes, electrical wires, fibre optics, etc. Thistype of pipes is called umbilicals in the technical jargon.

Also known are pipes that consist of combinations of one or moreumbilicals with e.g. a riser, an integrated production umbilical or anintegrated service umbilical.

In connection with tubular members of the above-mentioned type foroffshore use which are composed of several layers, some of which aretensile and/or compressive reinforcement layers, it is desirable to beable to detect the mechanical impacts on the pipe along its length,which may comprise great and unpredictable forces or very varyingtemperature impacts.

Sensors of the strain gauge type are frequently used for measuringforces that cause mechanical deformations, in which strain gauges theelectrical resistance in a conductor is changed by a mechanical impact.

Moreover, sensors are known where changes in the properties of anoptical component caused by mechanical deformations or temperaturevariations are monitored.

In connection with the use of the above-mentioned type of sensors formonitoring flexible pipes that may be several kilometers long, it isnecessary, of course, to run lines and/or optical fibres such that therecordings of the sensors may be monitored.

Sensors and transmission lines will hereinafter be referred to as asensor arrangement.

Clearly, the use of sensor arrangements of the above-mentioned type formonitoring flexible pipes requires that they be mounted well-protectedso that they are not damaged in use.

In connection with flexible pipes where the structure of the pipes is ofthe so-called unbonded type, i.e. the structure comprises severallayers, the layers must be capable of moving relative to each other inorder for the pipe to remain flexible.

Therefore, if the sensor arrangement was disposed freely between thelayers, it would quickly be damaged.

In view of this, the object of the invention is to provide a method ofmounting a sensor arrangement, ensuring that the sensor arrangement iswell protected against undesirable mechanical impacts and is thusoperationally reliable during the service life of the flexible pipe.

This object is achieved by the invention as defined in the claims.

In a first aspect, the invention relates to a method of mounting asensor arrangement in a tubular member, wherein at least a reinforcementlayer is provided on the tubular member by helical winding of an armorwire in such a way that the armor wire constitutes the reinforcementlayer. The method comprises the steps of:

-   a) providing at least one groove in the armor wire,-   b) filling the groove with a liquid material-   c) placing the sensor arrangement in the at least one groove to    thereby bringing the sensor arrangement into contact with the liquid    material, and-   d) fixing the sensor arrangement in the groove by solidifying the    liquid material.

The sensor arrangement is hereby “concealed” in the reinforcement layerin such a manner that impacts caused by a movement between the layers ofthe pipes have no harmful effect on the sensor arrangement, whereas theimpacts that should desirably be recorded, such as temperature ortensile stresses, may be recorded.

It is possible to provide the groove before initiating the helicalwinding, and, moreover, to perform the entire mounting of the sensorarrangement in the reinforcement layer so that the finish-mounted sensorarrangement may e.g. be stored on a coil before it is used as a pipereinforcement. Thus, the armor wire, which constitutes the reinforcementlayer when wound around the tubular member, may be stored on a coilwhile comprising integrated sensor arrangements. Moreover the materialof the armor wire is also the material of the reinforcement material.

This may be an advantage if the reinforcement of a pipe is to be woundat a location where there are no technical facilities for mounting thesensor arrangement in the reinforcement layer.

As mentioned above, it is preferred that the reinforcement layer is ahelical wound armor wire, e.g. of a metal such as steel, whichconstitutes the reinforcement layer, and optionally a tensile armor wirewhich constitutes the reinforcement layer. A metal or steel armor wireprovides sufficient strength to the tubular member and grooves mayrelatively easy be formed in a metal or steel armor wire with ordinarymetal or steel processing tools. In a preferred embodiment, the one ormore grooves are provided in the longitudinal direction of the armorwire.

Preferably the groove has a width of 0,5–5 mm and a depth of 0,5–5 mmand it is moreover preferred the groove is substantially U-shaped in thelongitudinal direction. Thereby the groove more easily receives thesensor arrangement, and less stress is induced into the reinforcementmaterial by formation of the groove.

Consequently it is preferred that the one or more grooves are formed bycutting or rolling. However the grooves may also be formed duringmanufacturing of the armor wire or wires, which constitute thereinforcement layer, e.g. during casting or molding.

The sensor arrangement may be brought into contact with the liquid byimmersing the sensor arrangement into the liquid or optionally theliquid may be arranged in spots or in one or more lines along the bottomof the groove. The liquid and the filling of the liquid into the groovewill be described in further detail later.

A preferred embodiment of the method according to the invention includesat least one groove, which groove comprises a bottom portion havinglower groove walls and an upper portion having upper groove walls. Thebottom portion is capable of containing the widest part of the sensorarrangement after the sensor arrangement has been placed in the groove.Furthermore, the method comprises the step of deforming the upperportion of the groove so that the upper walls of the groove are broughtcloser to each other than the width of the widest part of the crosssection of the sensor arrangement. Thus, it is possible to fix thesensor arrangement in a simple mechanical manner, which may be anadvantage when the liquid is not solidified. Moreover, a more stablefixation of the sensor arrangement in the groove is obtained.

In an alternative preferred embodiment of the method, one or both of theupper groove walls each are formed with at least one protrusion. Theprotrusion protrudes from the wall, prior to the deforming step, in adirection where it does not prevent the placing of the sensorarrangement. The one or more protrusions preferably constitute the partor parts of the upper wall or walls of the groove. In the deformingstep, the upper walls of the groove (and protrusions) are brought closerto each other than the width of the widest part of the cross section ofthe sensor arrangement.

The embodiment provides another method of fastening the sensorarrangement in the grooves in a simple mechanical way by deforming aprotrusion integrated with the groove. The protrusion is formed at theupper portion of the groove close to or integrated with the surface ofthe armor wire. The protrusion is advantageously formed in the sameprocess as the one or more grooves. The protrusion may be formed to runcontinuously along the grooves or as interrupted discrete protrusions.The upper walls of the groove or protrusion may be deformed in any knownway, selected according to material of the reinforcement layer in whichthe groove and optional protrusion are formed. Preferably, the uppergroove wall or protrusion is deformed by pressure e.g. using rollers.Preferably, the upper groove walls are deformed to partly or totallysurround the sensor arrangement, thereby securing a good fixation of thesensor arrangement in the groove. Moreover, in a relatively simple anduncomplicated embodiment the protrusions are constituted by edges formedat the upper portion of the groove.

In a preferred embodiment, the upper groove walls are deformed prior tothe application of the sensor arrangement in the armor wire. The uppergroove walls are deformed to a point where it is still possible to placethe sensor arrangement in contact with the liquid in the groove,preferably by pressing the sensor arrangement through the deformed uppergroove walls. To facilitate the placing of the sensor arrangement in thegroove, the upper groove walls may be only partially deformed or thedeformations may be formed as discrete deformations with a certain spacebetween neighbouring deformations. In one embodiment, the deformed uppergroove walls only have to keep the sensor arrangement in a fixedposition until the liquid has solidified, and the required fixingability of the deformed groove walls is only temporary. Consequently nopressure needs to be applied to the grooves after placing the sensorarrangement in the grooves, and undesired damage to the sensorarrangement due to pressure can be avoided.

However, for many purposes it is preferred that the upper groove wallsare deformed after the application of the sensor arrangement in thearmor wire. In this embodiment, it is relatively easy to place thesensor arrangement in the groove and a good fixation is obtained. Thedeformation may be performed all along the groove or only partiallyalong the extension of the groove in the longitudinal direction. If thedeformation is performed all along the groove, the best possiblefixation is obtained.

According to the invention, the sensor arrangement is fixed and anchoredin a solidified liquid. The liquid selected is able to adhere both tothe sensor arrangement and the reinforcement material. Moreover, theselected liquid has properties in the solidified state, which providesufficient flexibility to allow the solidified liquid to be formed intohelical windings corresponding to the helical windings of the armor wireforming the reinforcement layer. Preferred liquids will be described infurther detail later.

The sensor arrangement may expediently be immersed into the liquidmaterial and, preferably, it is immersed into the liquid material by theaction of a wheel positioned above the groove, said wheel having a facewhich is pressed against the sensor arrangement, following which thewheel immerses the sensor arrangement into the liquid material bypressure impact. The location of the sensor arrangement in the liquidmaterial may hereby be controlled so as to achieve the most optimumlocation.

For the mounting of sensor arrangements where no ultimate protection ofagainst mechanical impacts is required, the sensor arrangement maypreferably be mounted in liquid material, which is deposited pointwisein the groove, like discrete dots of liquid material. Moreover, thesensor arrangement may be only partially immersed in the liquid.

These preferred embodiments result in a saving of material, and it iseasier to make repairs on damaged pipes, since a portion of the sensorarrangement is located freely in the groove, which makes it relativelyeasy to make splices, etc. in the sensor arrangement.

According to the invention it is preferred that the liquid is a polymermaterial. Preferably the polymer material is thermoplastic plasticsand/or thermosetting plastics. By the term plastics is understoodpolymer material, which is able to undergo plastic deformation in theliquid state, but also, at least partially, in the solidified state.Thus, the solidified material poses flexibility and is able to withstanddeformation and twisting without cracking or loosening from the groovesin the reinforcement material.

Preferred polymer types for the polymer material are an epoxy type, avinyl ester epoxy, a polyurethane or mixtures containing one or more ofthese. Said polymers fulfil the requirements of the liquid according tothe invention. However, other liquids fulfilling the requirements mayalso be used according to the invention. The skilled person will be ableto select suitable liquids to be used according to the invention as amatter of routine.

The polymer material may preferably be fluorinated completely or partly.Such treatment may improve the properties of the polymer material withregard to wear resistance, chemical resistance and resistance towardselevated temperatures.

Furthermore, it is preferred that the polymer material is cross-linkedcompletely or partly. Cross-linking may improve strength and may beinitiated by heat, peroxides or other chemicals e.g. sulphur compounds.

In a preferred embodiment according to the invention, the one or moregrooves are coated with a coating layer after placing and/or fixation ofthe sensor arrangement in the one or more grooves. The coating layer mayimpart desired properties to the surface of the reinforcement layer andadditionally protect the sensor arrangement in the groove. The coatinglayer may comprise metallic and polymeric material and may be attachedby heat, hot melting, gluing etc.

An embodiment of the method according to the invention, which ispreferred for some purposes, comprises the steps of:

-   a) providing at least one groove in the armor wire,-   b) forming at least one protrusion at the upper portion of the    groove,-   c) filling liquid material into the groove,-   d) immersing the sensor arrangement into the liquid material,-   e) deforming the upper portion of the groove so that the at least    one protrusion partly surrounds the sensor arrangement, thereby    keeping the sensor arrangement in a fixed position, and-   f) solidifying the liquid material.

The embodiment is useful when a very strong fixation of the sensorarrangement in the groove is required.

In a further aspect, the invention also relates to a method of mountinga sensor arrangement in a tubular member, wherein at least areinforcement layer is provided on the tubular member by helical windingof an armor wire, which method comprises the steps of:

-   -   i. providing at least one grooves in the armor wire, which        groove comprises a bottom portion having lower groove walls and        an upper portion having upper groove walls,    -   ii. placing the sensor arrangement in the groove,    -   iii. deforming the upper portion of the groove so that the upper        groove walls are brought closer to each other than the width of        the widest part of the cross section of the sensor arrangement        contained in the groove after the sensor arrangement is placed        in the groove,        and where the bottom portion is capable of containing the widest        part of the cross section of the sensor arrangement.

The method provides a tubular member with at least one sensorarrangement, which is integrated and protected in the armor wireconstituting a reinforcement layer on the tubular member by use of onlymechanical fastening.

Preferably step i. is performed before the helical winding is initiated,preferably at least the steps i. and ii. or the steps i. and iii., morepreferably all the steps i.–iii. are performed before the helicalwinding is provided. Thereby it is possible to optimize the conditionsfor the manufacturing of the tubular member.

In order to obtain the best properties of the reinforcement layer it ispreferably constituted by an armor wire, which may be made of a metal,such as steel. Moreover, it is preferred that the groove is provided inthe longitudinal direction of the armor wire, which results in that thesensor arrangement is wound up helically around the tubular member withthe armor wire.

Preferably, the method comprises the further step of filling a liquidinto the groove and placing the sensor arrangement in the liquid andsolidifying the liquid. Hereby a much stronger fixation of the sensorarrangement is obtained.

In a preferred embodiment one or both of the upper groove walls each areshaped to have at least one protrusion. The protrusion is protrudingfrom the wall prior to the deforming step in a direction where it doesnot prevent the placing of the sensor arrangement, and the one or moreprotrusions preferably constitute the part or parts of the upper groovewall which in the deforming step are brought closer to each other tohave a mutual spacing, which is shorter than the width of the widestpart of the cross section of the sensor arrangement. Thus the sensorarrangement may easily be placed in the groove and a strong fixation maybe obtained.

Preferably, the upper groove walls are deformed by pressing the wallscloser to each other, preferably by pressing from the outer surface ofthe armor, e.g. by use of rollers. By selecting suitable rollers andpressure to be applied it is possible to deform the walls of the groovesin such a way that they are closing around and fixing the sensorarrangement, and preferably the upper groove walls are deformed topartly or totally surround the sensor arrangement, thereby keeping thesensor arrangement in a fixed position.

According to the method it may for some purposes be preferred that theupper groove walls are deformed prior to the application of the sensorarrangement in the armor wire. When the upper groove walls are deformedbefore the sensor arrangement is placed in the groove, the sensorarrangement of course has to be pressed down into the groove whilepassing the deformed upper groove walls. Preferably, the upper groovewalls are not deformed in the entire extension, but only in sections.This will facilitate the placing of the sensor arrangement in thegroove. Moreover, if the embodiment is used in combination with aliquid, with which the sensor arrangement is brought into contactwhereafter the liquid is solidified for fixing the sensor arrangement,the fixation ability of the deformed walls does not have to be veryhigh. In such case, the deformed walls only have to provide a temporaryfixation.

Alternatively, it is preferred that the upper groove walls are deformedafter the application of the sensor arrangement in the armor wire. Inthis embodiment it is easier to place the sensor arrangement in thegroove. Furthermore, the grooves may be deformed in their entireextension to obtain a good fixation. Although use of solidified liquidis not required in such a situation, it may be preferred in order toobtain a very strong and stable fixation of the sensor arrangement.

In a preferred embodiment, a liquid material is filled into the groove,pointwise or continuously, along the length of the groove after thesensor arrangement has been applied in the groove. The liquid is thensolidified to give a further fixation of the sensor arrangement.

Preferably the sensor arrangement is applied into the groove by theaction of a wheel disposed above the groove. The wheel has a face, whichis pressed against the sensor arrangement to place the sensorarrangement in the groove. Hereby the sensor arrangement can be placedin the groove by use of relatively simple mechanical means.

The liquid to be solidified is preferably a polymer material, andpreferably selected from the group of thermoplastic plastics, such as anepoxy type, a vinyl ester epoxy, a polyurethane or mixtures containingone of these, and thermosetting plastics.

Moreover, to obtain better strength and resistance against temperatureand environment, the polymer material is preferably fluorinatedcompletely or partly. Furthermore, in order to obtain better strength,the polymer material, when solidifying, is preferably cross-linkedcompletely or partly.

In a preferred embodiment of the method according to the invention, thegroove has a width of 0,5–5 mm and a depth of 0,5–5 mm, and preferablythe groove is U-shaped in the longitudinal direction. The groove is thencapable of housing most known sensor arrangements and the U-shapeensures that a minimum of stress is induced into the armor wire due tothe groove. The groove is preferably formed by cutting or milling.Optionally, the groove is formed during the manufacture of the armorwire.

Preferably the groove or the grooves are coated with a coating layerafter placing and/or fixation of the sensor arrangement in the groove.The coating layer may impart desired properties to the surface of thereinforcement layer and additionally protect the sensor arrangement inthe groove. The coating layer may comprise metallic and polymericmaterial and may be attached by heat, hot melting, gluing etc.

Optionally the sensor arrangement may also be fixed in the groove by useof clamps, screws, tape or similar fastening devices, at leasttemporarily. Furthermore, the embodiments of fastening the sensorarrangement in a groove may be combined in any desired way.

As mentioned, the invention also relates to a use.

This use is preferably for tubular members of the following types:

-   -   for the transport of water, gas and crude oil between        installations at an oil field    -   for the transport of process liquids from an installation        located at the surface of the sea and an oil well located below        the surface of the sea    -   for the transport of force-transferring fluids    -   umbilicals, and combinations of these.

In a further aspect, the invention also relates to a tubular membercomprising a sensor arrangement and at least one reinforcement layerprovided on the tubular member by helical winding, wherein a sensorarrangement is integrated or concealed in one or more grooves in thereinforcement layer by use of adhesion to the groove and/or by adeformation of the groove.

Consequently the invention also relates to a tubular member obtainableby any one of the methods described above.

The invention will now be explained more fully with reference to theembodiment illustrated in the drawings, in which

FIG. 1 shows the structure of a typical pipe for the transport of oiland gas,

FIGS. 2A–2D show cross-sectional profiles of reinforcement elements foruse as a reinforcement layer, and with sensor arrangements mountedaccording to the invention,

FIG. 3 shows a greatly distorted arrangement of sensors on a flexiblepipe corresponding to the sensor setup shown in FIG. 2D,

FIG. 4 is a cross-sectional, detailed and enlarged view of a sensorarrangement according to the invention which is mounted in areinforcement element,

FIG. 5 shows an end termination with a discharge duct for a sensorarrangement according to the invention, and

FIG. 6 shows a cross-sectional and enlarged view of an embodiment of theinvention in which the sensor arrangement is fixed by deformedprotrusions.

FIG. 1 shows an ordinary flexible pipe for use in the transport of oiland gas.

The pipe is composed of a carcass 2 around which an inner liner 3 isprovided, said liner being tight or diffusion tight so that no or onlylittle transport can take place from the interior of the pipe outwardstowards the surroundings, or vice versa. The carcass 2 is not tight, butits function is to prevent the inner liner 3 from collapsing because ofgreat external pressures which may occur e.g. as hydrostatic pressuresat great depths of water. Also the carcass may be used for protectionagainst abrasion.

Externally wound onto the inner layer is a pressure reinforcement layerwhich, as shown here, consists of joined C-profiles 5, 6. It is alsopossible to use other profiles, such as K-, Z- or X-profiles which arejoined with profiles of another type.

Externally applied to the reinforcement layer is a tensile reinforcementlayer which, as shown, consists of helically wound profiles 7, 8, whichare wound opposite each other at suitable angles, such as 20–55°,relative to the longitudinal axis of the pipe.

Finally, externally arranged onto the reinforcement layer is a tightjacket 9, which, however, may be omitted in some pipe structures.

FIGS. 2A–2B show embodiments of tensile reinforcement profiles incross-section, e.g. of the type which is shown at the reference numerals7 and 8 in FIG. 1, but are designated 10 a–10 d in FIGS. 2A–2D.

In FIGS. 2A–2D, the same reference numerals are used for the same parts,but with an added letter a, b, c or d, referring to FIG. 2A, 2B, 2C or2D.

As seen at the left-hand side of FIGS. 2A–2D, the profiles are formedwith grooves, while the right-hand side of the figures shows the sameprofiles, but now with one or more sensor arrangements mounted accordingto the invention.

FIG. 2A shows a tensile reinforcement profile which is generallydesignated 10 a. The profile has four faces which, in cross-section, aredesignated 11 a, 12 a, 13 a and 14 a, and, as will be seen, the faces 11a and 13 a are wider than the faces 12 a and 14 a. The face 11 a isformed with a groove 15 a, which is adapted to receive a sensorarrangement 16 a, see the right-hand side of FIG. 2A.

This sensor arrangement, which is positioned in the bending plane of thehelical winding, is particularly suitable for use in temperaturemeasurements, but may also be used for measuring variations in thestrains which occur on the reinforcement element because the pipecontracts or expands relative to a neutral value, which is defined asthe value that occurs when the helical winding has been completed in arest position on the pipe and forming a part of the reinforcement layer.

If, e.g. a very large tension occurs longitudinally of the axis of thepipe, then the sensor arrangement will sense it because of the loadingof the reinforcement element caused by this tension.

FIG. 2B shows the same profile as in FIG. 2A, but now formed with agroove 15 b which is positioned on one of the short faces, here shown atthe face 14 b, and with a sensor arrangement 16 b in the groove 15 b.

In this case, the sensor arrangement 16 b is positioned externally ofthe bending plane of the helical winding, which means that it issuitable for measuring a bend that occurs when the reinforcement elementis rotated relative to its longitudinal axis. Further, temperature mayalso be measured, of course, if the sensor arrangement contains atemperature sensor.

FIG. 2C shows the profile of FIG. 2B, but now with two grooves which aredesignated 15 c, each of which receives sensor arrangements 16 c.

In this case, the state of stress of the reinforcement element may bedetermined with two components, viz. a first component that originatesfrom axial deformation, and a component that originates from bendingaround the normal plane to the plane that is spanned by the two sensors.

In this case, too, the sensor arrangement may contain temperaturemeters, of course.

Finally, FIG. 2D shows the profile of FIG. 2C, but now with threegrooves 15 d formed in the side faces lid, 12 d and 14 d, and withsensor arrangements 16 d in the grooves 15 d. With this structure, itwill be possible to measure the axial deformation of the reinforcementelement and its complete extension in two planes as well astemperatures, if desired.

The mode of operation of the sensor arrangement will now be explainedwith reference to FIG. 3, which shows a structure of sensor arrangementscorresponding to the one in FIG. 2 d.

FIG. 3 shows a greatly distorted plane section through a flexible pipe,where 1 designates the pipe structure around which the reinforcementelements are wound.

In the figure, 10 d and 10 d′ indicate reinforcement elements.

Moreover, the individual sensor arrangements are designated 16 d, 16 da,16 db, 16 d′, 16 da′ and 16 db′.

Note that the axis of the pipe is not parallel with the axis of thereinforcement elements, as the reinforcement elements are twisted in ahelix around the axis of the pipe. This means that the reinforcementelement 10 d′ protrudes from the plane of the paper, and owing to thetwist the groove and thereby the position of the sensor arrangements in10 d′ is rotated relative to the location where the reinforcementelement is designated 10 d.

If it is assumed that the section through the pipe is made where thesensor arrangement is positioned, and if it is moreover assumed forreasons of understanding that the reinforcement elements are secured tothe pipe structure, bending of the pipe around the shown X-axis willmean that the sensor arrangements 16 d, 16 da and 16 db will recordsubstantially the same change in the state of strain of thereinforcement element, as, in this position, the reinforcement elementis subjected to a pure tension.

In contrast, bending around the X-axis cannot be recorded by the sensorarrangement 16 d′, since 16 d′ is positioned in the bending-neutral axisof the pipe, and therefore the effective strain is zero here.

Also, the sum of the recorded strains of the sensor arrangements 16 da′and 16 db′ will be zero, since 16 da′ and 16 db′ are subjected to thesame flexural tension, just with the opposite sign. Clearly, thereinforcement elements according to this invention need not be rigidlyfixed, but may slide across the pipe structure.

In this case, the above explanation will only apply approximately.

If the structure is subjected to compression, the reinforcement elementmay deflect in an uncontrolled manner. If e.g. a local bulging takesplace away from the pipe, this will be recorded in that the reading ofthe 16 d and 16 d′ sensors is not the same as the average of the readingof the 16 da, 16 db and 16 da′, 16 db′ sensors.

FIG. 4 shows in an enlarged view how a sensor arrangement according tothe invention is mounted in a groove, as is explained in connection withFIGS. 2A–2D.

10 designates a portion of a reinforcement profile, as shown in FIGS.2A–2D.

This is formed with a groove 16 where a sensor arrangement 17, 18, byway of example, is embedded by means of a material 19.

This material 19 is introduced into the groove 16 in a liquid state, andthen the sensor arrangement 17, 18 is immersed into the material. Thesensor arrangement may consist of an outer pipe 18, in which a fibre 17extends, said fibre being connected to an optical measuring component atsuitable distances longitudinally of the pipe 18. There may also beelectrical conductors in the steel pipe, which are connected to a straingauge.

Such sensor arrangements are generally known and will therefore not bedescribed more fully, as the details in connection with these have noimportance to the understanding of the invention.

The liquid material used may be many different types of polymermaterials, such as thermoplastic plastics, thermosetting plastics, epoxytypes, vinyl ester epoxy, polyurethane or mixtures of these.

Moreover, the polymer materials may be fluorinated completely or partlyand may be cross-lined completely or partly.

FIG. 5 shows an example of an end termination, which is intended as atap for a sensor arrangement mounted on a flexible pipeline.

The figure shows the flexible pipe of FIG. 1, but now with a sensorarrangement (not shown) according to the invention and mounted on an endtermination 20, 22. This end termination consists of a housing 20 whichis adapted to receive the pipe 1, and of an anchoring part 22 which issecured at one end to a termination point (not shown) and at the otherend to the housing 20.

The housing 20 is formed with a hole 21 through which optical fibres orelectrical conductors from the sensor arrangement extending in the cablemay pass.

As will be seen at the right-hand side of FIG. 4, optical fibres andelectrical conductors run via a duct 25 in the housing 22 which isconnected with one or more grooves in the tensile reinforcement of thecable.

Although FIG. 5 has been explained in connection with an endtermination, nothing, of course, prevents the same constructionalprinciples from being applied in connection with a bushing in which twocables are interconnected.

FIG. 6 discloses the principle of the embodiment of fixing the sensorarrangement in the groove by deforming protrusions. The reinforcementprofile 10, similar to the profiles of FIG. 2, is formed with anU-shaped groove 16 comprising protrusions A and B at the upper portion.The protrusions A and B may optionally be formed when the groove 16 iscut or when the reinforcement profile 10 is manufactured.

In the reinforcement profile 10′ a sensor arrangement 17, 18, comprisingfibre 17 and an outer pipe 18, has been placed in the groove 16′. Theprotrusions A′ and B′ are deformed into the groove 16′, thereby fixingthe sensor arrangement in the groove 16′. In the embodiment shown inFIG. 6, two protrusions A′ and B′ are used to fix the sensorarrangement. It is, however, understood the sensor arrangement may befixed by use of only one protrusion A′, if desired. Although theprotrusions A and B have been drawn to be very significant in FIG. 6,the protrusion may in principal be the edges on the upper portion of thegroove 16.

1. A method of mounting a sensor arrangement in a tubular member,wherein at least a reinforcement layer is provided on the tubular memberby helical winding of an armor wire, said armor wire being provided withat least one groove wherein said groove comprises a bottom portionhaving lower groove walls and an upper portion having upper groovewalls, said bottom portion being capable of containing the widest partof the sensor arrangement, said method comprising the steps of: a)filling the groove with a liquid material b) placing the sensorarrangement in the at least one groove to thereby bring the sensorarrangement into contact with the liquid material, c) fixing the sensorarrangement in the at least one groove by solidifying the liquidmaterial, and d) deforming the upper portion of the groove so that theupper groove walls are brought closer to each other than the width ofsaid widest part of the cross section of the sensor arrangement.
 2. Amethod according to claim 1 wherein step a) is performed before thehelical winding is initiated.
 3. A method according to claim 1, whereinat least the steps a–c), preferably the steps a–d) are performed beforethe helical winding is provided.
 4. A method according to claim 1wherein the reinforcement layer is constituted by a metal armor wire,preferably a steel armor wire.
 5. A method according to claim 1 whereinsaid at least one groove is provided in the longitudinal direction ofthe armor wire.
 6. A method according to claim 1 wherein one or both ofthe upper groove walls each are shaped to have at least one protrusion,said protrusion being protruding from the wall prior to the deformingstep in a direction where it does not prevent the placing of the sensorarrangement, said one or more protrusions preferably constituting thepart or parts of the upper groove wall which in the deforming step arebrought closer to each other than the width of said widest part of thecross section of the sensor arrangement.
 7. A method according to claim6 wherein the upper groove walls are deformed by pressing the wallscloser to each other, preferably by pressing from the outer surface ofthe armor, e.g. by use of rollers.
 8. A method according to claim 6wherein the upper groove walls are deformed to partly or totallysurround the sensor arrangement.
 9. A method according to claim 6wherein the upper groove walls are deformed prior to the application ofthe sensor arrangement in the armor wire.
 10. A method according toclaim 6 wherein the upper groove walls are deformed after theapplication of the sensor arrangement in the armor wire.
 11. A methodaccording to claim 1, wherein the sensor arrangement is immersed intothe liquid material by the action of a wheel disposed above the groove,said wheel having a face which is pressed against the sensorarrangement, following which the wheel immerses the sensor arrangementinto the liquid material by pressure impact.
 12. A method according toclaim 1, wherein the liquid material is deposited pointwise in thegroove.
 13. A method according to claim 1, wherein the sensorarrangement is only partially immersed in the liquid.
 14. A methodaccording to claim 1, wherein the liquid is a polymer material.
 15. Amethod according to claim 14, wherein the polymer material isthermoplastic plastics.
 16. A method according to claim 14, wherein thepolymer material is thermosetting plastics.
 17. A method according toclaim 14, wherein the polymer material is an epoxy type, a vinyl esterepoxy, a polyurethane or mixtures containing one of these.
 18. A methodaccording to claim 15, wherein the polymer material is fluorinatedcompletely or partly.
 19. A method according to claim 15, wherein thepolymer material in the solidifying step is cross-linked completely orpartly.
 20. A method according to claim 1 wherein the groove has a widthof 0,5–5 mm and a depth of 0,5–5 mm and preferably the groove areU-shaped in the longitudinal direction.
 21. A method according to claim1 wherein the at least one groove is formed by cutting or milling.
 22. Amethod according to claim 1 wherein the at least one groove is coatedwith a coating layer after placing and/or fixation of the sensorarrangement in the at least one groove.
 23. A method according to claim1 comprising the steps of: e) providing at least one groove in the armorwire, f) forming at least one protrusion at the upper portion of the atleast one groove, g) filling liquid material into the at least onegroove, h) immersing the sensor arrangement into the liquid material, i)deforming the upper portion of the groove so that the at least oneprotrusion partly surrounds the sensor arrangement, thereby keeping thesensor arrangement in a fixed position, and f) solidifying the liquidmaterial.
 24. A method of mounting a sensor arrangement in a tubularmember, wherein at least a reinforcement layer is provided on thetubular member by helical winding of an armor wire, said methodcomprising the steps of: i) providing at least one groove in the armorwire, said groove comprising a bottom portion having lower groove wallsand an upper portion having upper groove walls, ii) placing the sensorarrangement in the at least one groove, iii) deforming the upper portionof the groove so that the upper groove walls are brought closer to eachother than the width of the widest part of the cross section of thesensor arrangement contained in the groove after the sensor arrangementis placed in the groove, wherein said bottom portion is capable ofcontaining said widest part of the sensor arrangement.
 25. A methodaccording to claim 24 wherein step i. is performed before the helicalwinding is initiated, preferably at least the steps i. and ii. or thesteps i. and iii., more preferably all the steps i.–iii. are performedbefore the helical winding is provided.
 26. A method according to claim24 wherein the reinforcement layer is constituted by an armor wirepreferably of a metal, such as steel.
 27. A method according to claim 24wherein said at least one groove is provided in the longitudinaldirection of the armor wire.
 28. A method according to claim 24comprising the further step of filling a liquid into the groove beforeplacing the sensor arrangement in the groove, whereby the sensorarrangement is immersed in the liquid and in a subsequent step theliquid is solidified.
 29. A method according to claim 24 wherein one orboth of the upper groove walls each are shaped to have at least oneprotrusion, said protrusion being protruding from the wall prior to thedeforming step in a direction where it does not prevent the placing ofthe sensor arrangement, said one or more protrusions preferablyconstituting the part or parts of the upper groove wall which in thedeforming step are brought closer to each other than the width of saidwidest part of the sensor arrangement.
 30. A method according to claim24 wherein the upper groove walls are deformed by pressing the wallscloser to each other, preferably by pressing from the outer surface ofthe armor, e.g. by use of rollers.
 31. A method according to claim 24wherein the upper groove walls are deformed to partly or totallysurround the sensor arrangement.
 32. A method according to claim 24wherein the upper groove walls are deformed prior to the application ofthe sensor arrangement in the armor wire.
 33. A method according toclaim 24 wherein the upper groove walls are deformed after theapplication of the sensor arrangement in the armor wire.
 34. A methodaccording to claim 24, wherein a liquid material is filled into thegroove pointwise or continuously along the length of the groove afterthe sensor arrangement has been applied in the groove.
 35. A methodaccording to claim 24, wherein said sensor arrangement is applied intothe groove by the action of a wheel disposed above the groove, saidwheel having a face which is pressed against the sensor arrangement tothereby place the sensor arrangement in the groove.
 36. A methodaccording to claim 28, wherein the liquid is a polymer material,preferably selected from the group of thermoplastic plastics, such as anepoxy type, a vinyl ester epoxy, a polyurethane or mixtures containingone of these, and thermosetting plastics.
 37. A method according toclaim 36, wherein the polymer material is fluorinated completely orpartly.
 38. A method according to claim 36, wherein the polymer materialin the solidifying step is cross-linked completely or partly.
 39. Amethod according to claim 24 wherein the groove has a width of 0,5–5 mmand a depth of 0,5–5 mm and preferably the groove are U-shaped in thelongitudinal direction.
 40. A method according to claim 24 wherein theat least one groove is formed by cutting or milling.
 41. A methodaccording to claim 24 wherein the at least one groove is coated with acoating layer after placing and/or fixation of the sensor arrangement inthe at least one grooves.
 42. A method of mounting a sensor arrangementin a tubular member, wherein at least a reinforcement layer is providedon the tubular member by helical winding of an armor wire, said methodcomprising the steps of: j) providing at least one grooves in the armorwire, k) filling the groove with a liquid material l) placing the sensorarrangement in the at least one groove to thereby bring the sensorarrangement into contact with the liquid material, and m) fixing thesensor arrangement in the at least one groove by solidifying the liquidmaterial, wherein the sensor arrangement is immersed into the liquidmaterial by the action of a wheel disposed above the groove, said wheelhaving a face which is pressed against the sensor arrangement, followingwhich the wheel immerses the sensor arrangement into the liquid materialby pressure impact.
 43. A method according to claim 42 wherein step a)is performed before the helical winding is initiated.
 44. A methodaccording to claim 42, wherein at least the steps a–c), preferably thesteps a–d) are performed before the helical winding is provided.
 45. Amethod according to claim 42 wherein the reinforcement layer isconstituted by a metal armor wire, preferably a steel armor wire.
 46. Amethod according to claim 42 wherein said at least one groove isprovided in the longitudinal direction of the armor wire.
 47. A methodaccording to claim 42 wherein said groove comprises a bottom portionhaving lower groove walls and an upper portion having upper groovewalls, said bottom portion being capable of containing the widest partof the sensor arrangement contained in the groove after the sensorarrangement is placed in the groove, said method comprising the furtherstep of deforming the upper portion of the groove so that the uppergroove walls are brought closer to each other than the width of saidwidest part of the cross section of the sensor arrangement.
 48. A methodaccording to claim 42, wherein the liquid material is depositedpointwise in the groove.
 49. A method according to claim 42, wherein thesensor arrangement is only partially immersed in the liquid.
 50. Amethod according to claim 42, wherein the liquid is a polymer material.51. A method according to claim 50, wherein the polymer material isthermoplastic plastics.
 52. A method according to claim 50, wherein thepolymer material is thermosetting plastics.
 53. A method according toclaim 50, wherein the polymer material is an epoxy type, a vinyl esterepoxy, a polyurethane or mixtures containing one of these.
 54. A methodaccording to claim 51, wherein the polymer material is fluorinatedcompletely or partly.
 55. A method according to claim 51, wherein thepolymer material in the solidifying step is cross-linked completely orpartly.
 56. A method according to claim 42 wherein the groove has awidth of 0,5–5 mm and a depth of 0,5–5 mm and preferably the groove areU-shaped in the longitudinal direction.
 57. A method according to claim42 wherein the at least one groove is formed by cutting or milling. 58.A method according to claim 42 wherein the at least one groove is coatedwith a coating layer after placing and/or fixation of the sensorarrangement in the at least one groove.
 59. Use of the method accordingto claim 1 for mounting of a sensor arrangement in a tubular membersselected from the group consisting of tubular members: for the transportof water, gas and crude oil between installations at an oil field, forthe transport of process liquids from an installation located at thesurface of the sea and an oil well located below the surface of the sea,for the transport of force-transferring fluids, umbilicals, andcombinations of these.
 60. A tubular member comprising a sensorarrangement and at least one reinforcement layer provided on the tubularmember by helical winding, wherein said sensor arrangement is integratedor concealed in one or more grooves in the reinforcement layer by use ofa deformation of the groove with or without use of adhesion, said one ormore grooves comprises a bottom portion having lower groove walls and anupper portion having upper groove walls, said bottom portion beingcapable of containing the widest part of the sensor arrangement, saidtubular member being obtainable by a method comprising the step ofdeforming the upper portion of the groove so that the upper groove wallsare brought closer to each other than the width of said widest part ofthe cross section of the sensor arrangement.